1. Field of the Invention
This invention relates to a combustion cylinder structure for an oil burner, and more particularly to a combustion cylinder structure for an oil fired space heater of the type for radiating heat rays.
2. Description of the Prior Art
In the past, heat radiation from a combustion cylinder structure of an oil burner was carried out by red-heating a hemispherical wire mesh and/or a metal coil arranged on a top of the combustion cylinder structure by means of combustion heat produced in the structure and outwardly directly discharging heat rays emitted from the red-heated mesh and coil. Recently, however, it has been carried out by red-heating inner and outer perforated cylindrical members of the combustion cylinder structure between which fuel oil gas is thermally decomposed into combustible gas and outwardly discharging heat rays emitted from the red-heated cylindrical members through an outermost heat-permeable cylinder, as disclosed in Japanese Utility Model Publication No. 15254/1962, Japanese Utility Model Publication No. 50244/1981 and Japanese Utility Model Publication No. 13449/1984. In order to improve red-heating of the inner and outer cylindrical members, a part of through-holes of the outer cylindrical member is enlarged to cause combustion to be carried out on an outside of the outer cylindrical member as well as in a space between both cylindrical members. However, such construction, when combined with the wire mesh and/or metal coil described above, fails to satisfactorily red-heat them because of deteriorating function of discharging combustion gas from the combustion cylinder structure, accordingly, such wire mesh and metal coil are generally eliminated from the combustion cylinder structure.
Further, the combustion cylinder structure fails to sufficiently red-heat an upper portion of each of the inner and outer cylindrical members although a middle portion of each member is effectively red-heated, so that combustion efficiency is highly deteriorated. Also, This causes the upper portion of the structure to be seen blackishly, resulting aesthetic characteristics of the structure during combustion operation being deteriorated.
Accordingly, it would be highly desirable to develop a combustion cylinder structure for an oil burner which is capable of uniformly red-heating an upper portion of upper and lower cylindrical members of the structure as well as the remaining part of the members and exhibiting good aesthetic characteristics during combustion operation.